Between all the other usages, the Pluperfect Tense is also used for expressing somebody's or possible or even imaginary intention before the second action happened by way of interrupting or disabling the intention.

Seems to me that between all other its usages, the Pluperfect Tense is also used in phrases for expressing either possible or even imaginary intention that could happen before the second action happened at time of speaking and by way of interrupting or disabling the intention.

I picked up the flower before some other had done it.I got out before the bomb had exploded.